affair with long term friend and sexual partner

My husband admitted to being in love with the woman he tried to have a relationship with while we were separated. They both stated they considered each other best friends as well as sexual partners on and off for over 11 years. My husband keeps saying he's let her go. Recently he found that she is with someone new he is hurt by this. He still contacts her, he said they both agreed that they crossed the line when they tried to be more than friends. He keeps saying nothing will change with us all we do is argue and he's not happy. He forgets that i was hurt i forgave him but it still hurts. He says he loves me but he just don't know, but i believe he is more hurt by his actions and now she has moved on so quickly. I want to save my marriage how can i put the past behind and move forward start new without looking back.